Relative worked at this company.
As you can see, they had locations all over, and in fact he worked at one UK location and three overseas locations (in the country he was born in, so no "expat package"). Also means his degree was from "foreign" – I don't know if that matters?
I knew him slightly in person, but I've been researching the family history so happen to know quite a lot about him.
He was comfortably off in many ways. The children went through private school, but only with the help of bursaries. His wife became terminally ill (while overseas, no NHS), seriously affecting the family's financial situation both because of healthcare bills and because of childcare.
But he recovered from that situation – partly by remarriage.
He was definitely middle class: owned his own home, a car and a few shares; had at least two children go on to university. The family could afford to sail to between the UK and his birth country to visit family every now and then – although I know he combined it with work trips.
Thing is, if your character went to university... how did he get there in the first place? Was there family money? Doesn't have to be a lot, just a property here, or some shares there, or a legacy from gt-aunt Mabel. And his wife may be a similar class and have similar resources knocking about in the background.
For people in England (Scotland a little different) who came from families which could afford university in the 1920s, their income in the 1950s may well not be purely the result of their job...